diff --git a/vendor/google.golang.org/protobuf/proto/size.go b/vendor/google.golang.org/protobuf/proto/size.go
new file mode 100644
index 0000000..554b9c6
--- /dev/null
+++ b/vendor/google.golang.org/protobuf/proto/size.go
@@ -0,0 +1,97 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package proto
+
+import (
+	"google.golang.org/protobuf/encoding/protowire"
+	"google.golang.org/protobuf/internal/encoding/messageset"
+	"google.golang.org/protobuf/reflect/protoreflect"
+	"google.golang.org/protobuf/runtime/protoiface"
+)
+
+// Size returns the size in bytes of the wire-format encoding of m.
+func Size(m Message) int {
+	return MarshalOptions{}.Size(m)
+}
+
+// Size returns the size in bytes of the wire-format encoding of m.
+func (o MarshalOptions) Size(m Message) int {
+	// Treat a nil message interface as an empty message; nothing to output.
+	if m == nil {
+		return 0
+	}
+
+	return o.size(m.ProtoReflect())
+}
+
+// size is a centralized function that all size operations go through.
+// For profiling purposes, avoid changing the name of this function or
+// introducing other code paths for size that do not go through this.
+func (o MarshalOptions) size(m protoreflect.Message) (size int) {
+	methods := protoMethods(m)
+	if methods != nil && methods.Size != nil {
+		out := methods.Size(protoiface.SizeInput{
+			Message: m,
+		})
+		return out.Size
+	}
+	if methods != nil && methods.Marshal != nil {
+		// This is not efficient, but we don't have any choice.
+		// This case is mainly used for legacy types with a Marshal method.
+		out, _ := methods.Marshal(protoiface.MarshalInput{
+			Message: m,
+		})
+		return len(out.Buf)
+	}
+	return o.sizeMessageSlow(m)
+}
+
+func (o MarshalOptions) sizeMessageSlow(m protoreflect.Message) (size int) {
+	if messageset.IsMessageSet(m.Descriptor()) {
+		return o.sizeMessageSet(m)
+	}
+	m.Range(func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool {
+		size += o.sizeField(fd, v)
+		return true
+	})
+	size += len(m.GetUnknown())
+	return size
+}
+
+func (o MarshalOptions) sizeField(fd protoreflect.FieldDescriptor, value protoreflect.Value) (size int) {
+	num := fd.Number()
+	switch {
+	case fd.IsList():
+		return o.sizeList(num, fd, value.List())
+	case fd.IsMap():
+		return o.sizeMap(num, fd, value.Map())
+	default:
+		return protowire.SizeTag(num) + o.sizeSingular(num, fd.Kind(), value)
+	}
+}
+
+func (o MarshalOptions) sizeList(num protowire.Number, fd protoreflect.FieldDescriptor, list protoreflect.List) (size int) {
+	if fd.IsPacked() && list.Len() > 0 {
+		content := 0
+		for i, llen := 0, list.Len(); i < llen; i++ {
+			content += o.sizeSingular(num, fd.Kind(), list.Get(i))
+		}
+		return protowire.SizeTag(num) + protowire.SizeBytes(content)
+	}
+
+	for i, llen := 0, list.Len(); i < llen; i++ {
+		size += protowire.SizeTag(num) + o.sizeSingular(num, fd.Kind(), list.Get(i))
+	}
+	return size
+}
+
+func (o MarshalOptions) sizeMap(num protowire.Number, fd protoreflect.FieldDescriptor, mapv protoreflect.Map) (size int) {
+	mapv.Range(func(key protoreflect.MapKey, value protoreflect.Value) bool {
+		size += protowire.SizeTag(num)
+		size += protowire.SizeBytes(o.sizeField(fd.MapKey(), key.Value()) + o.sizeField(fd.MapValue(), value))
+		return true
+	})
+	return size
+}